Timing issues? 16197427 93 TBI

[TBI Tinker]

[Early TBI systems were designed with a number of redundancies. One of these is found in the ignition module. If the module is not in EST mode then it will very quickly ramp up spark advance when RPM reaches a threshold. There are different advance amount and different rpm thresholds based on the module part number, but most of the behavior described above should be considered normal.]

Copy that. I am comfortable with this now and I do see the repeatability at the threshold rpm as would be expected.

[What is not normal imo is the report that spark advance changes during backfire. Unless this is happening at the rpm threshold mentioned above, I would be tempted to investigate the aftermarket ignition parts. Is the rapid change you described what you were referring to by "jumping?"]

Agreed and I plan to still investigate this weekend. The jumping I was referring to is related to the dip in timing at the time of backfire while the EST is disconnected and the erratic behavior while the EST is connected. Erratic being the not-so-consistent retard values when accelerating at idle. That being said, I have only watched the timing with a light and I have not looked at it since I bumped the AE vs MAP values and smoothed the spark table. The adjustment seemed to attenuate the exhaust backfire and smooth out the throttle some. BUT that was one 20 minute session. Just enough to warm up, tinker for a minute and shut down for dinner. Should have more time this weekend to validate the improvements. My gut tells me it is likely related to the tune at this point.

[The values in this table represent injector "on" time. Larger values turn the injector on for a longer time, delivering more fuel. That engine will want much more fuel during acceleration enrichment than a stock TBI. I expect you will be working on the VE tables considerably as well.]

Copy that. Matches up perfectly with what I had in mind.

[If you have dyno software or a simulation for your engine you may save time using the shape of the torque curve to rough out the shape of your VE tables.]

I like this plan a lot. Sadly, the last time I ran Desktop Dyno it was on a floppy drive. I have been thinking about procuring a copy of the new program though. I have about a bajillion dollars wrapped up in kids video games. What's wrong with a little fun for dad right? Meh. we'll see.....that first program was really helpful to me back in the day though.

[If that Grumpy is the same Grumpy I knew, he was a very creative thinker with many good posts. If you can find some of the early ones they are likely to get you thinking about EFI and engines in ways you hadn't previously.]

It may very well be. I have read his and others posts till my brain was smoking considering what to do with this engine. Very insightful and he was good with relaying that very technical information in layman's terms. With a huge amount of resources. Huge. Truly dedicated individual as far as I could tell. Sadly I never knew him. But what a wealth of information. For real. I work in a very technically oriented field and the only way I can decompress sometimes is to read about other very technical but unrelated information. This site and TGO has been great for me. Truly appreciated.

[TBI Tinker]

[Anti-seize works as an excellent thermal conductor...better than the white paste. The copper based anti-seize is even better.]

HA! Is there no end to the usefulness of copper anti-seize?!?

[TBI Tinker]

Update

I had a chance to install a vacuum gauge. Pulls 15.5-16hg which fluctuates with engine RPM +- .5hg but not jittery like guides or shoddy valve lapping. Exhaust backfire seemed to get worse with double the AE VS MAP and AE vs TPS. Dies on hard throttle. Bogs like hell and dies [in gear].

Don't know HTH I could have possibly set it up 180 out but will check it tomorrow. Stranger things have happened I guess. Sure ACTS like its 180 out. If it NOT, really unsure what the step is next. Pondering the idea of setting up the 7427 for trans only. Just feels like pussin' out currently. Don't like quitting when the going gets tough. If it were a carb I would adjust the pump-shot. If no change I would check for 180 out. With the EFI I am not sure what steps to take next for an equivalent gut-check. Based on what I have read, AE vs MAP and AE vs TPS would be the ticket but I have not seen enough improvement to feel confident about it.

Hopefully, I can make some headway getting back to basics tomorrow. Almost hope its 180 out at this point but I like a challenge too.

Jeremy

[Fast355]

Update

I had a chance to install a vacuum gauge. Pulls 15.5-16hg which fluctuates with engine RPM +- .5hg but not jittery like guides or shoddy valve lapping. Exhaust backfire seemed to get worse with double the AE VS MAP and AE vs TPS. Dies on hard throttle. Bogs like hell and dies [in gear].

Don't know HTH I could have possibly set it up 180 out but will check it tomorrow. Stranger things have happened I guess. Sure ACTS like its 180 out. If it NOT, really unsure what the step is next. Pondering the idea of setting up the 7427 for trans only. Just feels like pussin' out currently. Don't like quitting when the going gets tough. If it were a carb I would adjust the pump-shot. If no change I would check for 180 out. With the EFI I am not sure what steps to take next for an equivalent gut-check. Based on what I have read, AE vs MAP and AE vs TPS would be the ticket but I have not seen enough improvement to feel confident about it.

Hopefully, I can make some headway getting back to basics tomorrow. Almost hope its 180 out at this point but I like a challenge too.

Jeremy

Check the firing order. Make certain you do not have cylinders 5 and 7 swapped. Has happened to me a couple of times. Runs but runs like crap with some exhaust popping. Not that far from Weatherford either.

Whats the fuel pressure doing when it is bogging. I have had a clogged filter/weak pump cause the pressure to drop with AE and adding AE have no effect.

Davis Unified is the only module I will run on these. Delco ones are the same crap as the cheap parts store ones now days. I have seen new ones fail out of the box on the module test machine.

[TBI Tinker]

Check the firing order. Make certain you do not have cylinders 5 and 7 swapped. Has happened to me a couple of times. Runs but runs like crap with some exhaust popping. Not that far from Weatherford either.

Whats the fuel pressure doing when it is bogging. I have had a clogged filter/weak pump cause the pressure to drop with AE and adding AE have no effect.

Davis Unified is the only module I will run on these. Delco ones are the same crap as the cheap parts store ones now days. I have seen new ones fail out of the box on the module test machine.

Thank you for the reply Fast355

I made the pilgrimage to our [mostly] local Summit Racing warehouse this weekend to pick up a DUI module and a fuel pressure adapter for the TBI. Sure is nice to have something local. I got spoiled when Super Shops as around.

Once I arrived back at the house, I promptly swapped the module. It made quite a difference in the cadence and attitude of the engine. Not sure if the module is that much better or if the one I removed was just sub-par but it did make a difference. In fact, it made a miss more pronounced which led me to pull the plugs. Black and ugly. two were likely fouled. I put in a set of hotter plugs [R45TS] Hopefully they will self-clean better until I get a chance to drive the truck around. Also, fuel pressure is rock steady @ 18psi in all conditions.

The engine is running MUCH better. The exhaust backfire is gone and no matter how hard I jab the throttle from idle while in park, it has no problems. In drive however, it still promptly bogs and dies.

I noticed on the scanner the other day, the TPS was reading .74 after I reset the Idle Air valve and base idle speed to improve the IAC counts. I suppose I will reset the TPS and IAC next. I originally had the IAC counts easily adjustable between 10 and 20. Now they are settling in around 40 when warm.

The other day when I adjusted the PE vs TPS and PE vs MAP I also moved the injector constant down to a smaller Lb/hr in an attempt to improve things related to acceleration. I will bump it back up. Hopefully it won't run so rich at idle.

I'm a little stumped on the bog/dying when in drive at this point. I feel good that the Module is working and the Spark plugs are good and the miss is gone. Fuel pressure is good. Double checked the distributor was stabbed correctly.

Will adjusting the VE table be my next move once I get the TPS/IAC reset?

Thanks again

[TBI Tinker]

Update

Well. It started as a beatutiful morning.

Truck running good enough I felt like hooking up, doing some emulation, capture some logs, do some tweaking, life is good. SO I get get the emulator working but the logging was not working for some reason. Meh, no biggy, -lets tweak something and see what happens. I had reverted the Lb/Hr back to a higher value so I was curious what change putting it back would make since I could do it in real time at this point. I hit send, it beeped. No change. Hmm interesting then about 5 seconds later, the RPMS drop out and starts barely running coughs, stumbles etc so I hurry and bump it back-up. It beeps. Says it sent. No change. Then about 5 seconds later, it dies. So I figured I must have dumped a bunch of fuel in by changing the BPW and fouled the plugs. Let's start it back up and see if we can burn some of the soot off the plugs. Hard start as expected, then dies. AH! I left the emulator connected maybe it didn't connect back up when I quickly cycled the key. Stop, disconnect, throw the chip back in. Hard start again but it starts. Get the rpm's up around 2500 for a minute or so. Backfiring through exhaust again. Meh, I'll pull the plugs polish them up and throw them back in there I think to myself. Let the RPM's off and it promptly dies.

Then I saw it.

Service Engine SOON. WTH I think. Hooked the scanner up and BOOM Code 42. Double checked, and yes Code 42. I reckon I just smoked the new Module.

So here is the question. Just for my personal edification. - Is it possible that when I put that big-fat .060 gap in the plugs that I overloaded the module? Is there something specific in the distributor I can check to see if the distributor is causing some issues?

Maybe I SHOULD have used the copper antiseize for the heatsink? ��

Anyhow appreciate any input.

Next step, verify FOR SURE it's the module, procure a new one and start-over. I guess I can throw the one I just removed in there for a quick test but I won't leave it in. The D.U.I. module worked much better IMO.

[stew86MCSS396]

Failsafe will cause a solid check engine light and run like dookie. Be sure to disable the checksum before emulating with the auto prom. If you don't you'll go into failsafe mode the first time you make a change. The larger cam will pull less vacuum, causing the engine to run rich at idle and low load. You're definitely going to have to work on your VE tables and spark tables. Installing a wideband will make dialing in the VE tables a lot easier. For AE, I'd start by adjusting AE vs MAP. You may not need to add much to AE vs TPS. If you don't need the high volume pump, it's probably better to put a standard one in. Less load on the distributor gear.

You have not acknowledge if you've done this. Failsafe/check engine light/service engine soon/SES light/Limp Home Mode..whatever you want to call it. I can speak for myself that this does happen when you upload a change while emulating and you have NOT disabled the checksum. Hover over the parameter tree where it says "Read me" and look for some kind of tidbit about disabling the checksum while emulating.

[Kitch]

Whenever I've had an emulation problem (had the check engine light come on and it run rough in limp home mode) I've had to pull both the PCM fuses or disconnect the battery, only then could I successfully upload the last good bin I was running on and get it all running good again.

[stew86MCSS396]

Whenever I've had an emulation problem (had the check engine light come on and it run rough in limp home mode) I've had to pull both the PCM fuses or disconnect the battery, only then could I successfully upload the last good bin I was running on and get it all running good again.

Yup I concur. Should've mentioned that once I saw a cel, dash data in tprt would get wonky and/or non responsive. Only way to get over that hurdle was to clear the codes and try again.

[TBI Tinker]

You have not acknowledge if you've done this. Failsafe/check engine light/service engine soon/SES light/Limp Home Mode..whatever you want to call it. I can speak for myself that this does happen when you upload a change while emulating and you have NOT disabled the checksum. Hover over the parameter tree where it says "Read me" and look for some kind of tidbit about disabling the checksum while emulating.

Thank you for the feedback stew86mcss396

I have at least attempted to do-so. I put AA in the same place I found $OD. Perhaps I misunderstood what I was reading. I didn't realize there was a comment directing where to put the AA. I will check it out. I may have put the AA in the wrong location. Is it possible it should be $AA instead of AA?

[TBI Tinker]

Whenever I've had an emulation problem (had the check engine light come on and it run rough in limp home mode) I've had to pull both the PCM fuses or disconnect the battery, only then could I successfully upload the last good bin I was running on and get it all running good again.

Thank you for the reply Kitch

If resetting using the battery disconnect will work it would really make make day. I attempted clearing the codes using the scanner but it didn't even blink. it stayed set unlike the previous Code 42's I cleared that were set when by disconnecting the EST wire.

[TBI Tinker]

Update

Pulling the battery power reset the computer and all is good in the world again. Thank you for the gimme. I'm still new at this EST thing as you can tell I'm sure.

The Mask I am using displays the Mask ID in hex so it is not required to specify the $ before the AA. I am sure I had the checksum disabled.

That being said, I had some issues getting Emulation/Logging working this morning. It would say it was communicating but it did not actually work. I got to tinkering and found an option to 'Initialize Emulation Hardware' I clicked it and sure enough the Logging started working. I had some stuff to do today so I opted to just log and not emulate but I feel reasonably confident it too will work now. Not sure if that had anything to do with the malfunction yesterday or not. I am thinking it would not run at all while the emulator is plugged in if it wasn't actively passing information.????

I made some headway with the bog/dying I was experiencing. I noticed I had an advance timing value of 23k+ when the bog was happening. I remembered reading about it previously so I went back and found http://www.gearhead-efi.com/Fuel-Inj...-Advance/page2 from Dec 2019 started by Jimmie. As a result, I zero'd the Main spark Bias and the Altitude Spark Bias. Made quite a difference. I could actually get off the line without it dying on me although the bog was still evident. Next I turned the Injector lb/hr value down to 64 lb/hr from 84 lb/hr. Still bogs slightly initiating hard throttle from a stop but man - it really woke up.

So here's the deal I am wondering about now. Obviously I need more fuel and we can get there from here with either higher pressure or bigger injectors or both. I am good with this.

Question is WTH does this thing WANT to pull a crap-ton of timing coming off idle? This has me stumped. I don't like the idea of leaving the spark Bias at ZERO as it gets pretty warm here in the summer and I have no doubt it will make a difference on the tune when it warms back up. I am concerned detonation weather is around the corner and I rather like the option of going negative to save the engine when it's hot. I have a feeling the timing will be high across the board at this point since I just removed the Bias values. I will capture that in the next session

Is the timing issue related to the MAP increase on sudden throttle? That's where I will be looking next. I don't to mask the root cause with removing the Spark Bias.

As always, appreciate any input.

[Fast355]

Update

Pulling the battery power reset the computer and all is good in the world again. Thank you for the gimme. I'm still new at this EST thing as you can tell I'm sure.

The Mask I am using displays the Mask ID in hex so it is not required to specify the $ before the AA. I am sure I had the checksum disabled.

That being said, I had some issues getting Emulation/Logging working this morning. It would say it was communicating but it did not actually work. I got to tinkering and found an option to 'Initialize Emulation Hardware' I clicked it and sure enough the Logging started working. I had some stuff to do today so I opted to just log and not emulate but I feel reasonably confident it too will work now. Not sure if that had anything to do with the malfunction yesterday or not. I am thinking it would not run at all while the emulator is plugged in if it wasn't actively passing information.????

I made some headway with the bog/dying I was experiencing. I noticed I had an advance timing value of 23k+ when the bog was happening. I remembered reading about it previously so I went back and found http://www.gearhead-efi.com/Fuel-Inj...-Advance/page2 from Dec 2019 started by Jimmie. As a result, I zero'd the Main spark Bias and the Altitude Spark Bias. Made quite a difference. I could actually get off the line without it dying on me although the bog was still evident. Next I turned the Injector lb/hr value down to 64 lb/hr from 84 lb/hr. Still bogs slightly initiating hard throttle from a stop but man - it really woke up.

So here's the deal I am wondering about now. Obviously I need more fuel and we can get there from here with either higher pressure or bigger injectors or both. I am good with this.

Question is WTH does this thing WANT to pull a crap-ton of timing coming off idle? This has me stumped. I don't like the idea of leaving the spark Bias at ZERO as it gets pretty warm here in the summer and I have no doubt it will make a difference on the tune when it warms back up. I am concerned detonation weather is around the corner and I rather like the option of going negative to save the engine when it's hot. I have a feeling the timing will be high across the board at this point since I just removed the Bias values. I will capture that in the next session

Is the timing issue related to the MAP increase on sudden throttle? That's where I will be looking next. I don't to mask the root cause with removing the Spark Bias.

As always, appreciate any input.

Don't play with the bias values. Set those to stock and leave them alone. All you are doing is manipulating the timing value with the wrong values. The 23K reading is the result of a negative timing value. You need to increase the spark map on that area to get the timing advance positive again. With Vortec heads I almost never have any value in the timing table under about 8 or 10°.

[TBI Tinker]

Don't play with the bias values. Set those to stock and leave them alone. All you are doing is manipulating the timing value with the wrong values. The 23K reading is the result of a negative timing value. You need to increase the spark map on that area to get the timing advance positive again. With Vortec heads I almost never have any value in the timing table under about 8 or 10°.

Copy that. I really had no intention of leaving it this way. I see the removal of the Spark Bias as a troubleshooting step not a permanent fix. I believe I have identified I need better fuel mapping and better spark mapping at this point. It did help e to clearly identify I need more fuel. Initially I wasn't sure due to the negative timing hitting at the same time.

I just finished reading this post where Dave w had a similar issue. http://www.gearhead-efi.com/Fuel-Inj...ED-sorta/page2

Not sure what came of it but Dave w linked his issue(s) to the Altitude Spark Bias. Here is a link to the service bulletin referred to in the post by 1project2many also http://ww2.justanswer.com/uploads/he...gine_knock.pdf

I did not try removing the Altitude Spark Bias first. I just yanked them both. I will put the Standard Bias back in first as a test. If nothing else, I can capture a range of what the timing would look like to provide the same performance as a baseline for working the spark map. It seems counter intuitive to add enough Spark to counter act the Spark Bias though. I would feel a lot better if I could quantify why this thing WANTS to pull so much timing out to begin with. I guess that's what bothers me the most at the moment.

I will use your numbers as the lower limit reference now to give me an idea where I am during the process as I try to learn what this engine wants. Really appreciate your input sir.

I will leave the fuel alone and put the Spark Bias back in. Maybe it just wants the fuel?

Thanks again

[TBI Tinker]

OKay Fast 355.

I am better understanding the spark timing scheme now and your comment about raising the tables in that area are jiving now.

If I am wrong here, please correct me.

The main spark Bias is always subtracted in the timing calculation. I was not understanding that initially. I was thinking it is only applied under certain circumstances. In fact, it is always used and the effect shifts depending on the spark table it is looking at. This way it is not required to have many spark bias' set up to handle the varying conditions.

Anyway, question now is, WHEN does the Altitude Spark Bias come into play? I put the Main Spark Bias back into the program without negative effect but I have not put the Altitude Spark bias in yet. Is there a specific table it is associated with in $OD?

I am glad I pulled the Bias' out because it quantified a problem and even gladder I didn't melt anything. Maybe not the best plan I ever had.

Thanks,
Jeremy